Magnetic resonance angiography (MRA) in renally impaired patients: when and how.

Magnetic resonance angiography (MRA) and NSF in renally impaired patients have a close relationship due to the frequent coincidence of vascular and renal pathologies, the relatively large amount of contrast media applied and the delayed excretion. The date of the first NSF cases described in literature falls into the development of multi-stationary MRA--an investigation that requested multiple bolus injections or one large bolus of the contrast agent. It is therefore easily understood that NSF was regarded initially as possible complication of MRA. A review on the history of MRA is presented and various techniques for MRA are described. While many neuroradiological indications can be solved by native MRA, most angiographic indications throughout the body rely on the application of intravenous contrast agents. The paper discusses options for alternative methods in vascular imaging and offers guidelines for patients with renal impairment. NSF must always be balanced versus the outcome of an investigation, respectively versus the outcome of a denied MRA. Moreover, in patients with chronic kidney disease (CKD) and a proper justification for a vascular investigation, neither CT angiography nor DSA should replace MRA. Restrictions in contrast media dose for CKD patients are mandatory and obviously reduce the risk of NSF. Gadolinium-based contrast agents with lower stability are now contraindicated in patients with reduced renal function. The role of blood pool agents is under evaluation. Since the awareness of the new disease grew over the last year, radiologists were able to reduce the number of newly diagnosed NSF cases by more careful consideration of contrast application and agent in renally impaired patients, which gives hope that NSF can be avoided by respecting some easy rules.